2. ASEXUAL VS SEXUAL REPRODUCTION
A S E X U A L
R E P R O D U C T I O N SEXUAL REPRODUCTION
•C R E AT E S
I D E N T I C A L
C O P I E S
( C L O N E S )
•O N LY I N V O LV E S
M I T O S I S
•O N E PA R E N T
I N V O LV E D
•C O M M O N I N
B A C T E R I A A N D
U N I C E L L U L A R
P R O T I S T S
•Adds genetic variation
•Involves meiosis and
fertilization
•TWO parents involved
•Diploid and haploid cells
3. MITOSIS AND MEIOSIS
M I T O S I S MEIOSIS
•O N E D I V I S I O N
•2 N → 2 N
• (same number of chromosomes)
•R E S U L T S I N 2
G E N E T I C A L L Y
I D E N T I C A L C E L L S
•Two divisions
•2n → n
• Half the number of chromosomes
•Results in 4 DIFFERENT haploid
cells
•Forms gametes (egg and sperm)
4. We have two genes for each trait
– this is our GENOTYPE
One gene came from mom, one
from dad
If the genes are alike, the
individual is homozygous (RR,
rr)
If the genes are different , they
are heterozygous (Rr)
Some genes are dominant and
others are recessive
We only show a recessive trait if
we have no dominant gene
RR and Rr would
“look” dominant
rr would look
recessive
This diagram shows the cross
between 2 heterozygous purple
flowers
Cross is: Bb x Bb
Notice that 75% are purple and
25% white
GENETICS
5. Females are XX
Males are XY
Sex-linked traits are
on X chromosome
Trait is more
common in MALES
Examples are
colorblindness and
hemophilia (blood
fails to clot)
SEX LINKAGE
• Males give X chromosomes to
their daughters and Y’s to their
sons
• Moms give X’s to both
daughters and sons
6. • Four blood types
▪ A, B, AB, O
Three different
alleles: A, B or
neither
A = AA or AO
B = BB or BO
AB = AB
O = OO
CODOMINANCE – BLOOD TYPE
Agglutinogen
= protein
7. PEDIGREES
Tracing traits through
generations
• Males are squares
• Females are circles
• Horizontal line means
married
• Vertical line means children
• Filled in circle means the
individual HAS the
condition
• Can you identify the
genotypes of individuals 4,
7, 12?
4 = Ee (parent 2 had to give an e)
7 = Ee (child is ee, so they had to have one
e)
12 = ee (affected with recessive condition)
8. • In humans, 22 pair of
autosomes
• 1 pair of sex chromosomes
• XX = female
• XY = male
• Extra chromosomes a result
of non-disjunction
• Chromosome pairs fail to separate in
meiosis
• One example is DOWN SYNDROME (extra
21)
• Another example is KLINEFELTERS (XXY)
XY = male
3 21’s =
Down
Syndrome
